Heating devices



May 29, 1956 'L. D. DRUGMAND 2,748,251

HEATING DEVICES Filed April 20. 1953 I WW M w IN V EN TOR.

L 5? TE R D. DRUGMHND Fl-rronwgy United States Patent f HEATING DEVICES Lester D. Drugmand, Pittsburgh, 12's., assignor to Edwin L. Wiegand Company, Pittsburgh, Pa., a corporation of Pennsylvania Application April 20, 1953, Serial No. 349306 Claims. (Cl. 219-68) My invention relates to a method for securing two members together to provide a unitary structure and to the article of manufacture produced thereby, more particularly to an improved electric heater and the method of producing the same, and the principal object of my invention is to provide new methods and articles of manufacture of the character described.

In the past, sheathed electric immersion heaters of the flange-mounted type have been secured to a mounting flange by welding, silver soldering and the like. However, these prior art constructions have not been entirely satisfactory for various reasons.

Foremost among the disadvantages of prior art constructions is the high cost of manufacture, the fragility of the assembled unit, and the difiiculty of obtaining a leak-proof joint between the flange and the sheathed heating element.

My invention is superior to prior art constructions with respect to the points mentioned above and it additionally possesses other advantages that will become apparent from a study of the following description and of the drawing appended hereto.

In the drawing accompanying this specification and forming a part of this application there is shown, for purpose of illustration, an embodiment which my invention may assume, and in this drawing:

Figure 1 is a perspective view of a flange-mounted, sheathed electric immersion heater embodying my invention,

Figure 2 is an enlarged sectional view generally corresponding to the line 22 of Figure 1 and illustrating certain parts prior to final assembly, and

Figure 3 is an enlarged view similar to Figure 2 but illustrating certain parts after final assembly.

As best seen in Figure l, the embodiment of my invention therein illustrated comprises a generally U-shaped, sheathed heating element 10 of conventional design having its leg portions extending through and secured to a mounting flange 11.

As will be clear, the element 10 is adapted to be inserted through an opening in the wall of a vessel such as a water heater tank so that it extends interiorly thereof. It is then adapted to be secured in position by bolting the mounting flange, which is adapted to overlie the opening in the tank, against the wall of the tank. Since the foregoing is in accordance with the conventional usage of electric immersion heaters, further description thereof is believed to be unnecessary.

Referring to Figures 2 and 3, wherein one of the two similar legs of the heating element 10 is shown, it will be seen that the heating element It; comprises the usual tubular sheath 12 filled with refractory material 13 in which is embedded a conventional resistance wire (not shown). Terminal pins 14 are electrically connected by any suitable means to the resistance wire disposed within the sheath 12 and extend from respective ends of the sheath to provide for the required electrical connections.

In the presently disclosed embodiment, a bushing 15,

preferably having an outside diameter slightly smaller than the interior of the sheath and an inside diameter slightly larger than the terminal pin, is adapted to be disposed interiorly of and adjacent to a respective end of the sheath and about a respective terminal pin. Ordinarily, the sheath 12 is adapted to be swaged after it has been filled with refractory material and after the bushings 15 have been positioned within the sheath, this swaging operation reducing the diameter of the sheath and thus compacting the refractory material 13 about the imbedded resistance wire. The swaging operation will crimp the sheath 12 about the bushings 15 and prevent loss of refractory material from the ends of the sheath during subsequent handling. It is to be understood, however, that under certain conditions the bush ings 15 may be eliminated and the refractory material extended to the ends of the sheath.

In the embodiment of the. invention herein disclosed, the bushing 15 is formed of a plastic resin having di electric properties and having considerable compressive strength but being resilient and deformable under pressure; however, it will be apparent that the bushing 15 may be formed of any material possessing the requisite characteristics.

The flange ll is provided with spaced-apart apertures 16 through which the terminal portions of the respective le s of the heating element 11 extend. As illustrated in Figure 2, wherein one of the apertures 16 is shown, each aperture is considerably larger than the cross-sectional size of the adjacent part of the heating element and is tapered for a purpose to be shown, the smallest portion of each aperture 16 in the disclosed embodiment being disposed adjacent the terminal end of a respective leg of the heating element.

in assembling the heating element it with the mount-, ing flange ill, the element is disposed in the position shown in Figure 2 wherein terminal portions of the legs of the element are disposed within respective apertures 16. A sleeve 17, shown in dot-dash lines in Figure 2, and formed of copper or other material flowable under pressure, is then disposed about each of the terminal portions of the legs of the element as shown.

The flange El and the heating element 1d are adapted to be supported in the position shown in Figure 2 in any suitable manner while dies (not shown) which are engageable with opposite ends of respective sleeves 17 are urged toward each other by means of a press or the like. As the dies are urged toward each other, opposite ends of respective sleeves 17 will be upset so as to overlie the aperture in as shown in Figure 3 and each sleeve will be deformed to fluid-tight engagement with side surfaces of the flange ii and with the marginal surface of the respective aperture 16. It will be appreciated that the die portions engageable with the sleeves 17 will be formed with cavities that will contain the ends of the sleeves and mold them to the configuration illustrated.

As will be clear, the compressive force exerted upon a sleeve it? by the dies will reduce the internal diameter of the sleeve and cause it to press against and partially collapse the sheath 12. The bushing 15 disposed interiorly of the sheath will prevent complete collapse thereoff; however, the bushing 15 will be deformed by the partially collapsed sheath and will be further tightly compressed between the sheath and the terminal pin 14.

It will thus be obvious that my invention provides for securing the heating element it? and the mounting flange ill together to provide a permanently assembled, unitary structure. Additionally, since the bushing 1.5 is tightly compressed between the inner wall of the sheath and the terminal pin 14-, the interior of the sheath is adequately sealed against the entrance of foreign matter.

As before mentioned, the apertures 16 in the flange 11 are tapered to a reduced diameter in a direction toward the terminal end of the sheath. This is done so that high pressure developed within the tank will tend to wedge the heater assembly more tightly together and thereby relieve the upset ends 17a of the sleeves 1'7 of any strain which might otherwise be developed in resisting such pressure.

I11 view of the foregoing it will be apparent to those skilled in the art that I have accomplished at least the principal object of my invention and it will also be apparent to those skilled in the art that the embodiment herein disclosed may be variously changed and modified, without departing from the spirit of the invention, and that the invention is capable of uses and has advantages not herein specifically described, hence it will be appreciated that the herein disclosed embodiment is illustrative only, and that my invention is not limited thereto.

I claim:

1. An immersion heater for use with water heater tanks and the like, comprising a sheathed-type heating element, a mounting member for securing said heater to the tank, said member having a tapered aperture through which said heating element extends, and sleeve means interposed between said heating element and said mounting member and molded under pressure into intimate relation with respective adjoining surfaces to provide a unitary assembly, the tapered aperture in said mounting member and the corresponding taper of said sleeve means providing for wedging the various parts of said immersion heater together with increasing force when pressure is developed in the interior of the tank.

2. An electric heater, comprising a deformable sheathed-type heating element having a terminal pin disposed within the sheath, a mounting flange having an aperture through which said heating element extends, a deformable member disposed within said sheath and about said terminal pin in position adjacent said flange, and sleeve means interposed between said sheath and said flange and molded under pressure into intimate relation with respective adjoining surfaces, opposite ends of said sleeve means being upset adjacent the aperture in said flange to effect interlocking interengagement therewith and the wall of said sheath being forced by said sleeve means into tight sealing relation with said deformable member and said deformable member being forced into tight sealing relation with said terminal pin.

3. In an electric heating element of the type comprising a sheath enclosing refractory material in which is embedded a resistance conductor having a terminal portion extending outwardly of an opening in the terminal end of said sheath, the method of connecting the terminal end of said sheath in fluid-tight relation to a mounting flange having a transverse opening of a size loosely receiving the cross-sectional size of said terminal end, which comprises inserting a tubular member of deformable material between the wall of said flange opening and the exterior surface of said terminal end, and pressing said member to deform and expand laterally with sufficient force to indent the terminal end of said sheath and to completely occupy the space between said flange opening wall and the exterior surface of the indented terminal end and to intimately engage with said wall and said exterior surface in fluid-tight relation, whereby the sheath of said heater is connected to said mounting flange in fluid-tight relation and is locked against axial displacement.

4. In an electric heating element of the type comprising a metal sheath enclosing refractory material in which is embedded a resistance conductor having a terminal portion extending outwardly of an opening in the terminal end of said sheath, the method of connecting the terminal end of said sheath in fluid-tight relation to a metal mounting flange having a transverse opening of a size loosely receiving the cross-sectional size of said terminal end, which comprises inserting a tubular member of malleable metal between the wall of said flange opening and the exterior surface of said terminal end, and pressing said member to deform and expand laterally with suflicient force to indent the terminal end of said sheath and to completely occupy the space between said flange opening wall and the exterior surface of the indented terminal end and to intimately engage with said wall and said exterior surface in fluid-tight relation, whereby the sheath of said heater is rigidly connected to said mounting flange in fluid-tight relation and is locked against axial displacement.

5. In an electric heating element of the type comprising a metal sheath enclosing refractory material in which is embedded a resistance conductor having a terminal portion extending outwardly of an opening in the terminal end of said sheath and a dielectric deformable plug inserted into the terminal end of said sheath and about said terminal portion, the method of closing the opening in said terminal end and of connecting the terminal end in fluid-tight relation to a metallic mounting flange having a transverse opening of a size loosely receiving the cross-sectional size of said terminal end, which comprises inserting a tubular member of malleable metal between the wall of said flange opening and the exterior surface of said terminal end, and pressing said member to deform and expand laterally with sufl'icient force to indent the terminal end of said sheath and press said dielectric plug into intimate engagement with the inner surface of said sheath and the adjacent defining surface of said terminal portion, and further to completely occupy the space between said flange opening wall and the exterior surface of the indented terminal end and to intimately engage with said wall and said exterior surface in fluid-tight relation, whereby the sheath of said heater is rigidly connected to said mounting flange in fluid-tight relation.

6. An electric heater assembly, comprising a heating element including a metal sheath enclosing refractory material in which is embedded a resistance conductor having a terminal portion extending outwardly of an opening in a terminal end of said element, a metal mounting flange having a transverse opening of a size loosely receiving said terminal end, and a tubular member of malleable metal in the peripheral space between the wall defining said flange opening and the exterior wall surface of said sheath at said terminal end, said member having been expanded laterally with sufficient pressure to indent said sheath at said terminal end and to intimately engage with the terminal end wall surface and the flange opening wall in fluid-tight relation.

7. An electric heater assembly, comprising a heating element including a metal sheath enclosing refractory material in which is embedded a resistance conductor having a terminal portion extending outwardly of an opening in a terminal end of said element, a deformable plug disposed within the opening at said terminal end and about the adjacent portion of said resistance conductor, a metal mounting flange having a transverse opening of a size loosely receiving said terminal end, and a tubular member of malleable metal in the peripheral space between the wall defining said flange opening and the exterior wall surface of said sheath at said terminal end, said member having been expanded laterally with sutlicient pressure to indent said sheath at said terminal end to compress said plug between the inner wall of said sheath and the adjacent portion of said resistance conductor, thereby forming a closure for said sheath opening, and said member having been pressed into intimate engagement with the terminal end wall surface and the flange opening wall to provide a rigid fluid-tight connection between said heating element and said flange.

3. An electric heater assembly, comprising a heating element including a metal sheath enclosing refractory material in which is embedded a resistance conductor having a terminal portion extending outwardly of an opening in said element, a mounting flange comprising a generally flat plate having a through transverse opening of a size loosely receiving the sheath of said element to provide a recess which surrounds said sheath and being of a length equal to the thickness of said flange, and a deformable tubular member disposed in said recess and deformed by axial pressure to laterally expand into intimate engagement in fluid tight relation with the facing surfaces of said sheath and said recess whereby said sheath and said flange are rigidly held together by a leak-proof joint.

9. An electric heater assembly as specified in claim 6 wherein said mounting flange has a face which intersects said transverse opening and wherein said member has a portion which projects outwardly of said opening beyond said face and which has a radial enlargement larger than said transverse opening.

10. An electric heater assembly as specified in claim 6 wherein said heating element has a heat-generating portion disposed on one side of said mounting flange and wherein the latter has a face adjacent to said heat-generating element portion and which intersects said transverse opening and wherein said member has a portion which projects outwardly of said opening beyond said face and which has a radial enlargement larger than said transverse opening.

References Cited in the file of this patent UNITED STATES PATENTS 557,174 Turner Mar. 31, 1896 582,698 Scott .a May 18, 1897 914,808 Daniels Mar. 9, 1909 1,770,824 Abbott July 15, 1930 2,155,239 Randolph Apr. 18, 1939 2,617,009 Hasley Nov. 4, 1952 

